In general, the invention relates to a mechanically deformable container type dispenser for submerged discharge of a quantity of liquid from the dispenser into liquid surroundings. More particularly, the dispenser is a type wherein the wall structure of an orificed container is comprised by a flaccid membrane, with which opposed end effectors at the ends thereof are combined in a manner whereby said end effectors constitute means for applying tension to the wall structure in order to actuate dispenser operation.
All embodiments of the invention are capable of operation unattended at a submerged site in a surrounding liquid of a first composition, releasing thereinto--at a low rate of discharge--a liquid of a second composition.
To clarify by example what is meant by `low rate`, an approximately palm-sized unit embodying the invention has been used to discharge two hundred and fifty (250) milliliters of liquid over a period of about five hundred (500) hours--nearly three weeks--thus averaging a discharge of only about 0.5 milliliters per hour. After opening a previously closed orifice in this small unit, the user simply allows the unit, which is appropriately weighted, to sink into the liquid body which will receive the `dose` of liquid automatically discharged from such a pre-filled packet-like product.
There are numerous purposes to which embodiments of the invention may be applied with advantage, in preference to a considerable diversity of known types of dispensers which also possess utility for unattended submerged discharge of a liquid at a low rate. Some devices for submerged dispensing are known wherein the liquid specifically to be discharged is displaced from a container by allowing a different liquid thereinto, drawn either from the surroundings or from a separate container elevated higher than the immediate liquid surroundings of the dispenser container, in order to develop an excess of hydrostatic pressure. Such approaches are limited to a somewhat narrow range of applications, however, because pre-discharge admixture of some displacement liquids and some dispensed liquids is highly unfavourable to maintaining constant compositional qualities of the latter, for the comparatively long period of time entailed by a low discharge rate. Furthermore, in view that the dispenser containers for carrying out such approches are typically rigidly constructed, ie. with rigid wall structure, such dispensers occupy as much submerged volume after discharging their contents as before, and this can be undesirable when unobstructed space within the liquid surroundings is at a premium.
The invention is excellently suited to replenishment or preservation of a chemical constituent which is intended to be maintained at a certain concentration in a liquid body that may be subjected to some foreseeable type of depletion process. Depletion processes which the invention is useful to counteract may include any of the following: evaporative loss of volatile constituents; alteration of constituents due to chemical reaction; precipitative deposition of solutes; nutritive consumption of constituents by biological organisms; and removal by mechanical means of constituents which adhere to surfaces of articles dipped into and retracted from a liquid body.
Although the genesis of the invention in its earliest embodiments was in the context of swimming pool treatment means to assure a desired quality of pool water, and to reduce swimming pool operating costs, it should be noted that most if not all of the foregoing depletion processes may in many instances be normally incurred in settings of use wherein a particularly constituted and/or treated liquid body is employed for productive purposes in such fields of enterprise as the following: chemical processing in general; liquid waste treatment; biotechnology (including fermentation of beverages and culture of anti-biotic medicines); aquaria; mariculture; agriculture (including paddy cultivation, and hydroponics); floriculture; decorative garden ponds; animal husbandry; and textile processing (dip dyeing).
Swimming pool and therapeutic spa treatments employing the invention have to date been more thoroughly investigated from a marketing standpoint, but any one or more of the foregoing diverse types of enterprises may well ultimately consume a larger number of tension-actuated submerged dispensers constructed in accordance with the invention. For example, needed nutritional supplements for cattle and hogs are very conveniently provided by means of tension-actuated dispensers submerged in drinking troughs or in-the-ground livestock drinking reservoirs (`waterholes`), and it seems reasonable to suppose that the number of such troughs and waterholes, on a worldwide basis, far exceeds the total number of swimming pools and spas.